The ICG mostly operates on the honour system, but people often do know who has won what.

The important thing about the ICG system is that it isn't all about rank. Your 'rank' only matters in the context of the next masquerade you enter; it isn't a special badge meant to give you prestige or anything. People misinterpret this a lot, so it bears repeating. The ICG system is designed to keep high-level costumers from competing at low levels, not to keep low-level costumers from competing at high levels. Anyone can compete at a higher level if they wish.

So you do not have to strictly adhere to the 3-major-awards rule if you don't want to - if you've been sewing for years and have lots of experience but have never won an award, under the ICG system you can enter in Journeyman or even Master if you like. You won't necessarily win an award, of course, but if you feel that's where you belong because of your skills, you can do that. All the ICG system does is keep people like Masters from competing against Novices, because once you've won an award at a higher level you can't go back down to the lower level.